rayon/iter/
filter_map.rs

1use super::plumbing::*;
2use super::*;
3
4use std::fmt::{self, Debug};
5
6/// `FilterMap` creates an iterator that uses `filter_op` to both filter and map elements.
7/// This struct is created by the [`filter_map()`] method on [`ParallelIterator`].
8///
9/// [`filter_map()`]: ParallelIterator::filter_map()
10#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
11#[derive(Clone)]
12pub struct FilterMap<I, P> {
13    base: I,
14    filter_op: P,
15}
16
17impl<I: Debug, P> Debug for FilterMap<I, P> {
18    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
19        f.debug_struct("FilterMap")
20            .field("base", &self.base)
21            .finish()
22    }
23}
24
25impl<I, P> FilterMap<I, P> {
26    /// Creates a new `FilterMap` iterator.
27    pub(super) fn new(base: I, filter_op: P) -> Self {
28        FilterMap { base, filter_op }
29    }
30}
31
32impl<I, P, R> ParallelIterator for FilterMap<I, P>
33where
34    I: ParallelIterator,
35    P: Fn(I::Item) -> Option<R> + Sync + Send,
36    R: Send,
37{
38    type Item = R;
39
40    fn drive_unindexed<C>(self, consumer: C) -> C::Result
41    where
42        C: UnindexedConsumer<Self::Item>,
43    {
44        let consumer = FilterMapConsumer::new(consumer, &self.filter_op);
45        self.base.drive_unindexed(consumer)
46    }
47}
48
49// ////////////////////////////////////////////////////////////////////////
50// Consumer implementation
51
52struct FilterMapConsumer<'p, C, P> {
53    base: C,
54    filter_op: &'p P,
55}
56
57impl<'p, C, P: 'p> FilterMapConsumer<'p, C, P> {
58    fn new(base: C, filter_op: &'p P) -> Self {
59        FilterMapConsumer { base, filter_op }
60    }
61}
62
63impl<'p, T, U, C, P> Consumer<T> for FilterMapConsumer<'p, C, P>
64where
65    C: Consumer<U>,
66    P: Fn(T) -> Option<U> + Sync + 'p,
67{
68    type Folder = FilterMapFolder<'p, C::Folder, P>;
69    type Reducer = C::Reducer;
70    type Result = C::Result;
71
72    fn split_at(self, index: usize) -> (Self, Self, Self::Reducer) {
73        let (left, right, reducer) = self.base.split_at(index);
74        (
75            FilterMapConsumer::new(left, self.filter_op),
76            FilterMapConsumer::new(right, self.filter_op),
77            reducer,
78        )
79    }
80
81    fn into_folder(self) -> Self::Folder {
82        let base = self.base.into_folder();
83        FilterMapFolder {
84            base,
85            filter_op: self.filter_op,
86        }
87    }
88
89    fn full(&self) -> bool {
90        self.base.full()
91    }
92}
93
94impl<'p, T, U, C, P> UnindexedConsumer<T> for FilterMapConsumer<'p, C, P>
95where
96    C: UnindexedConsumer<U>,
97    P: Fn(T) -> Option<U> + Sync + 'p,
98{
99    fn split_off_left(&self) -> Self {
100        FilterMapConsumer::new(self.base.split_off_left(), self.filter_op)
101    }
102
103    fn to_reducer(&self) -> Self::Reducer {
104        self.base.to_reducer()
105    }
106}
107
108struct FilterMapFolder<'p, C, P> {
109    base: C,
110    filter_op: &'p P,
111}
112
113impl<'p, T, U, C, P> Folder<T> for FilterMapFolder<'p, C, P>
114where
115    C: Folder<U>,
116    P: Fn(T) -> Option<U> + Sync + 'p,
117{
118    type Result = C::Result;
119
120    fn consume(self, item: T) -> Self {
121        let filter_op = self.filter_op;
122        if let Some(mapped_item) = filter_op(item) {
123            let base = self.base.consume(mapped_item);
124            FilterMapFolder { base, filter_op }
125        } else {
126            self
127        }
128    }
129
130    // This cannot easily specialize `consume_iter` to be better than
131    // the default, because that requires checking `self.base.full()`
132    // during a call to `self.base.consume_iter()`. (#632)
133
134    fn complete(self) -> C::Result {
135        self.base.complete()
136    }
137
138    fn full(&self) -> bool {
139        self.base.full()
140    }
141}
rayon/iter/filter_map.rs

rayon/iter/
filter_map.rs
